Objective: To determine the clinical significance of the cytoplasmic dot anti-"nuclear" antibody (ANA) staining pattern.
Methods: We describe a patient with fatigue, arthralgias, elevated serum transaminase, and antibodies staining 5-20 cytoplasmic dots in HEp-2 cells. A liver biopsy revealed the presence of Stage III primary biliary cirrhosis (PBC). Using 2-color immunofluorescence, we determined the relationship between the cytoplasmic dot staining pattern and that produced by antibodies directed against the GW182 component of mRNA processing bodies. To determine the prevalence of the cytoplasmic dot staining pattern in patients with PBC, sera from 493 patients were tested for antibodies producing this staining pattern.
Results: Antibodies in our patient's serum colocalized with anti-GW182 antibodies in cytoplasmic dots, but did not react with recombinant GW182, suggesting that they were directed against an additional component(s) of these structures. The cytoplasmic dot staining pattern was observed in 21 of 493 (4.3%) patients with PBC. In comparison, this staining pattern was not produced by serum from 248 patients with other autoimmune diseases.
Conclusion: A subset of patients with PBC have autoantibodies that produce the cytoplasmic dot staining pattern. These antibodies react with one or more as yet unidentified components of the mRNA processing body. Appreciation of the clinical significance of the cytoplasmic dot staining pattern may assist in appropriate diagnosis and treatment of patients with PBC.